Not breeders FARMS. N MOST LIKELY CAME FROM OVERSEAS,POWER FEEDING, IN LINE BREEDING CAUSES THESE DEFORMITIES. .. Sorry to Burst your bubble but it's a runt. Now if it has sentimental value to you. Enjoy.
I could see hobbyists keeping a deformed fish, but I agree professional breeders cull even perfectly formed runts. At least among the African breeders I've come into contact with. The fry are so numerous. I got 180 calvus babies from one female in one batch of eggs. Mbuna can spit 20-60 babies every six weeks.
If you find a place that will buy 40 of the same fish at one time let me know. Or any of those fish for $20 each. Most hobbyists that sell are lucky if they break even.